I've never done low-carb (no bread?? HAHAHA no thanks), but my husband and some of our friends jumped hard on the Atkins bandwagon when it became popular. My husband and two of his friends were dizzy, tired and nauseous for the entire first two weeks. It's apparently common and called the "Atkins flu" or "induction flu," and it's your body's reaction to the switch to low carbs. It resolved within the first few weeks for our two friends, my husband ended up quitting
But hey, you gave it an honest try and if it's not for you, so what? It's so important to find a WOE that works for you, that makes you happy and that's effective. I could never do low-carb - and I totally admire anyone who can - but I've found something else that works great and I'm happy!